Questions tagged [function-construction]
For questions on writing functions (pure or using Set/SetDelayed) for any purpose, including the features that may be incorporated in those functions, such as options, patterns and conditions.
2,415
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Change the function-defined solution domain to fit NDSolve original Interpellation domain
Given a system of coupled non-linear equations, I used NDSolve to solve it in the domain of:
$$ -10^{50} \le r \le 10^{50} $$
...
1
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2
answers
95
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How to construct a custom-made matrix conditional on a set of rules?
The following code does what I intend to achieve; however, it is too cluttered for a simple matrix operation. I like to reduce the code to a one-line code as a ...
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Creating function with array input with desired coefficient and evaluate it
I had asked the same question before here Creating a list of functions with desired coefficients
but did not get the desired answer, may be I was not clear in my question.
I have defined this function ...
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1
answer
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Creating a list of functions with desired coefficients
I have defined this function to results some list of functions, however its not returning what I want
...
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2
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161
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First argument -h is not a valid variable
I am trying to simpligy my life by defining a function that gets the series expansion of $f(x+h)$ and $f(x-h)$ (at $x=0$) by the following code,
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1
answer
73
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Map list of strings to appropriately nested functions
I have a list of strings consisting of sequences of "+" or "-"'s. For example, let's take the list
...
- 561
2
votes
2
answers
123
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Can I write a function that describes a hysteron?
Is there a way to write a "function", or as the answer below refers it better as a memory, that has the following output:
k=0 if the last time x was outside the range (a,b), it was x<a. ...
- 197
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31
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Defining a function for FunctionCompile[]
Lets say that I have the definition EQN4 that is determined from some calculation. If I run it in a cell, I get the following output:
...
- 23
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3
answers
69
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Define function to test arguments and set value to 0 (application 0 Log [0] = 0)
I have an expression that has the form
f1[a, b, c] Log[ f2[a, b, c] ]
Now if f1[a,b,c] and ...
- 977
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36
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How to calculate this hierarchy in Mathematica?
A hierarchy can be defined as follows:
$F_0(n) = 1 $ when n = 1, 0 for all other values
$F_{\alpha+1}(n) = \sum_{i=1}^nF_\alpha(i)$
$F_{\alpha}(n) = F_{\alpha[n]}(n)$ when $\alpha$ is a limit ordinal
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2
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2
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79
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How can I Save function defintion without its DownValues?
I use functions that memorize their values like this one:
...
- 749
2
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2
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119
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Write Integral in Ostrogradsky's Method Form
Lets say we want to integrate
$$\tag{1}F(x) = \frac{3 x^5-x^4+2 x^3-12 x^2-2 x+1}{\left(x^3-1\right)^2}$$
One approach might be to write it in partial fraction form and then integrate each fraction ...
- 3,044
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1
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71
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How to make a polynomial output be used as function for input?
I basically made a code interpolating a set of data that gives me the polynomial for the interpolation. Here's the sample interpolation I did.
...
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41
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Defining function through a formula
I would like to define a cocycle on a group that maps into the unit circle. That is, I want to be able to define a function $f:G\times G\to\mathbb{T}$ such that $f(e_G,a)=f(a,e_G)=1$ for all $a\in G$ ...
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Is it possible to use the Finite Fields package to define the elements of GF(4) in terms of the irreducible polynomial $P$?
I am new to the Finite Fields package and am finding the package tutorial confusing.
I am wondering, if I am working over GF[4], is there a way of finding the elements of GF[4] in terms of the ...
- 481
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1
answer
86
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How to code retarded time in Lienard-Wiechert potential equations?
I have been making strides on my project with the help of others here but have run into another snag: I am having difficulty in expressing the Lienard-Wiechert potentials with retarded time. For ...
- 55
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4
answers
110
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Interpolation of missing matrix values
Problem statement
I want to replace missing matrix values, denoted by an integer 0, with the Mean of their surrounding values.
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1
answer
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Nearest inside Minimize
How to use Nearest inside Minimize?
The following returns errors but if # - {a, b} is ...
- 9,568
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3
answers
297
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Plotting multiple parametric 3D curves without using the Show command
How can I plot multiple parametric 3D curves on a single graph without the need to combine them using Show? Additionally, is there a way to clearly distinguish ...
- 2,411
2
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1
answer
122
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Evaluation control in function definition: Total interferes with Evaluate
Here is a simple example to illustrate my problem:
...
- 387
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votes
1
answer
98
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How to express a retarded time function?
I have been messing around with Lienard-Wiechert potentials and am having some trouble properly expressing my retarded time function. As of this moment the function looks like so
...
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1
answer
123
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Creating a plot for a summation function
I have this potential function which I believe is representative of a grounded cube in a 3D plane. I'm not entirely sure if this is it, but here is the general solution of the function:
v(x,y,z) = G(...
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1
answer
114
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How can I effectively input more than two list arguments into a function?
I am trying to input more than two list arguments into a function. For example, I have written the following code:
...
- 169
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1
answer
59
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Appying Function To All Elements Of A Long List vs Over List's First Element Gives Different Results
So, I have two lists, and a function. If I apply my function to both lists in a "listable" manner, I have one result, but if I apply it to lists' elements one-by-one, in a "map" ...
- 345
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1
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112
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Succinctly plotting a function defined in terms of many intermediate functions
I'm trying to plot a function that is in turn defined in terms of a lot of other functions, which each have a lot of variables. Here's a stylized example of the kind of thing I'm trying to do:
...
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97
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Why won't this magnetic field plot?
I have been having some longstanding trouble in getting a 2D vector plot of a magnetic field to show up. For context, I am working with Lienard-Wiechert potentials and as such trying to plot the curl ...
- 55
5
votes
4
answers
320
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Show positions of duplicated matrix elements
1. Problem statement
I want to replace duplicated elements within a matrix with a placeholder value.
2. Example data
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- 47.5k
5
votes
6
answers
340
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Swap lists and sequences
I'm looking for a function which does the following:
ListSequenceSwap[{6, {1, 2, 3}, 4, 5, {2, 2}, {4}}]
{{6}, 1, 2, 3, {4, 5}, 2, 2, 4}
...
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0
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81
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Is there a way to optimize it for larger n?
This is Domen's code from my previous thread here. I think it covers all the cases that I mentioned there and works well for small values of n. However, for large ...
- 2,411
4
votes
8
answers
482
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Delete list elements above a certain threshold
1. Problem statement
Going from right to left, I want do delete all elements after they have occured n times. The solution I found seems to work reliably, but is ...
- 47.5k
4
votes
2
answers
567
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How to calculate equivalent resistance for a network of same-value resistors?
Let's assume I have n identical resistors. I can connect them either in series or in parallel (let's disregard bridge connections for now). Now, I want to list all ...
- 2,411
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36
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Commutator for Solving Coefficients in a Hamiltonian
I am relatively new to Mathematica but I understand the basics.
I want to solve for coefficients by commutator constraints and I have problems implementing the commutator. The setup is the following:
...
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1
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1
answer
60
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How to remove terms with negligible constant from expression? [closed]
I'm working on a Notebook that requires the integration of multiple expressions (sometimes numeric, sometimes analytic). These expressions are normally of the form:
...
0
votes
1
answer
74
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Using Part[[i]] to defined a function
I would like to define a function like this
f[x_, v_] := Part[m, 4, 1]
where m = {{x^2}, {x^3}, {x^6}, {v x^4}}. but I can't ...
- 345
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votes
1
answer
225
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Okhsl colour space
I am trying to recreate the Okhsl colour space from here. Below are the hue-saturation plots desired:
I can create something similar (code adapted from here) with
...
- 8,152
2
votes
1
answer
72
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Function to Save/DumpSave without specifying full path
I am trying to create a function that saves a set of symbols into "test.mx" and is easy to use.
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votes
2
answers
112
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Can't we find the range of values for this formula?
This algebraic expression is as follows:
s=a/(a + b + c) + b/(b + c + d) + c/(a + c + d) + d/(
a + b + d)
where the parameters a, b, c, and d are all greater ...
- 2,879
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2
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60
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Understanding SetDelayed, ":=" [closed]
Consider the example below,
p = {1, 2, 3};
x = {x1,x2,x3};
fun[x_] := {{1, 0, 0}, {0, 1, 1}} . (p + x);
fun2[x_] = {{1, 0, 0}, {0, 1, 1}} . (p + x);
I expected <...
- 91
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51
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Comparing graphs in mathematica: shape vs. name
I'm trying to identify and remove duplicate graphs when contracting vertices. To illustrate this, I'll start with two simple graphs where I'm trying to create a function that can recognize them as ...
- 2,688
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0
answers
43
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Graphics3D with projected/flat eye view? [closed]
Following image can be perceived as a cube (a regular hexagon with 3 internal line segments) :
But in mathematica, it is not possible to make such shape with rotation.
Examples of some close state of ...
- 4,047
4
votes
2
answers
191
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Graphic3D, white face, black edge in any view?
Graphics3D[
Cuboid /@ Complement[Tuples[{1, 2, 3}, 3], {{1, 2, 3}, {3, 1, 3}}],
ViewPoint -> {45.42, -83.46, 31.83}, Boxed -> False]
Above code generates ...
- 4,047
2
votes
3
answers
81
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What is the best way to redefine a function that has type ambiguity 0/0 at an isolated point?
Consider the following Green Function of wire turn producing magnetic field:
...
- 749
14
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1
answer
1k
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Visualizing gravity warping the fabric of spacetime
What is a stable way of creating a set of points that are attracted to a single moving point? I have tried the following:
...
- 8,152
2
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1
answer
202
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Solving Schrödinger equation for Dirac comb potential (kicked rotor)
I need to solve the Schrödinger equation for a Dirac delta potential. I could not find the correct way to write the time-dependent potential and how to solve the time-dependent equation for it.
The ...
- 1,524
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1
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77
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Is there any other good way to convert an algebraic expression into a specified form?
The original algebraic formula is:
((-a^2 + b^2) k)/Sqrt[(1 + k^2) (b^2 + a^2 k^2)]
To convert to:
...
- 2,879
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0
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57
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Using compile with indexed variables
I have the following piece of code which I made faster by using compile. I make the following definitions
...
- 185
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1
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57
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-1
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1
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Difficulty in Proving Symbolic Equality in Mathematica [closed]
I'm currently working with the Mathematica software to verify the symbolic equality between two mathematical expressions. However, I've encountered a challenge where Mathematica's symbolic ...
- 99
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1
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65
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A problem of Mathematica function with different parameters in the same model
I'm simulating a graph of a function, and have made a preliminary attempt with mathematica, my test code is as follows::
...
- 103
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1
answer
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Function[0], Function[,0], and Function[{},0]: Is there any inherent distinction in the "academic" sense?
Note that Function[,0] is by default interpreted as Function[Null,0].
The following three calls all give ...
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